The size that actually matters: 1280×720
YouTube's published recommendation for a custom thumbnail is 1280 × 720 pixels, a 16:9 aspect ratio, and the minimum accepted width is 640 pixels. 1280x720 is what this tool produces by default, and it's the size that displays sharply across search results, the up-next sidebar, the homepage grid and, importantly, large TV screens — a surprising share of YouTube viewing now happens on a living-room television, where an undersized thumbnail looks visibly soft next to the video beside it.
Uploading larger doesn't make it sharper
YouTube serves thumbnails at 1280x720 or smaller in almost every placement, regardless of what resolution you upload — so a 4K thumbnail and a 1280x720 thumbnail of the same crop look identical to a viewer. What a larger source photo does help is the crop itself: starting from a higher-resolution original gives the focal-point crop more detail to work with before quality drops, which matters if you're cropping in tightly on a face or a product. The uploaded thumbnail file itself doesn't need to exceed 1280x720 to look correct.
Why crop around a focal point instead of the centre
Very few source photos are already 16:9. A portrait selfie, a screenshot, a product photo shot in a different ratio — getting any of these to 1280x720 means cropping something, and a centred crop only works when the subject happens to already be in the middle. Dragging the focal point onto the face or object that has to read clearly builds the crop around that point instead, so a subject standing to one side of the original photo still ends up centred and legible in the thumbnail.
Design for small and covered
A thumbnail is judged at a fraction of its real size — often under 200 pixels wide in a mobile feed — and the bottom-right corner is covered by the video duration badge on most layouts. Two practical consequences follow from that:
- Keep the main subject — a face, the key object, any text you've added elsewhere — inside the central two-thirds of the frame, clear of the duration badge corner.
- Favour a small number of large, high-contrast elements over anything fine or detailed; detail that reads clearly at full size disappears at thumbnail scale.
This tool crops and resizes a photo to the right dimensions; it doesn't add text or graphic overlays. If your thumbnail needs a title treatment or arrows and circles, add those in an image editor after exporting the 1280x720 crop, so the photo underneath is already correctly framed.
File format and size
YouTube accepts JPG, PNG or non-animated GIF for custom thumbnails, capped at 2MB. This tool exports JPEG at high quality, which comes in well under that limit for a 1280x720 image while keeping the crop sharp — there's no need to compress it further afterwards.
Everything runs in your browser using the canvas API. The photo is never uploaded to a server, there's no account or sign-up, and no file size limit beyond what your own device can handle.